The invention relates to a method and an apparatus for the treatment of contaminated, especially infected materials, in which the latter are fed through a feed hopper to a screw conveyor, heated and disinfected or sterilized, and emptied through a discharge.
A high-temperature disinfection apparatus for hospital wastes has been disclosed by DE 39 38 546 C2, in which the wastes are fed through a feed hopper to two screw conveyor sections separated by pressure-tight mechanical locks. In the first screw conveyor section a steam pressure is adjustably produced by heat input, while in the second screw conveyor section a vacuum is produced in order to remove moisture from the material by drawing off the vapors. In this known apparatus it is a disadvantage that mechanical pressure locks are used, which are complicated and also give trouble. Since leakage must always be expected, such mechanical pressure locks are not suitable for assuring the pressure conditions necessary for disinfection. In addition, the screw system sections are arranged in the horizontal plane, so that contaminated fluid can flow unnoticed through the apparatus and pass through this process untreated or improperly treated. There is no assurance that under all conditions a reliable disinfection, and especially sterilization of the wastes, will be accomplished.
The invention is based on the object of providing a process and an apparatus which by using simple technical means will always assure a reliable disinfection and sterilization of contaminated materials, and in which energy consumption will also be optimized.
This object is achieved in accordance with the invention by the features of claim 1, as well as of claim 16. Further description of the invention will be found in the dependent claims.
Since the materials are fed to a first screw conveyor which is configured as a heating screw conveyor wherein a compression of the material takes place such that a sealing plug of material is produced in its end area, the material is released at the end of the heating screw conveyor into a treatment chamber and expands therein, the material in the area of the treatment chamber passes into a second screw conveyor which is configured as a treatment conveyor, controlled bursts of energy are introduced into the treatment conveyor, steam is delivered or produced and an excess pressure and the necessary temperature are built up and maintained, and in the end part of the treatment screw conveyor the material is compressed to form a second, sealing plug of material, it has been accomplished that, between the two constantly and automatically forming plugs of material providing a good seal, an excess pressure that is very advantageous to the process can be maintained over a long path for a defined period of time.
Preferably, the material in the heating screw conveyor, which is arranged to feed upward at an angle, is transported upwardly. This reliably prevents contaminated fluid from the area below the feed hopper from flowing unnoticed into the apparatus and possibly passing through the process untreated or improperly treated. The angle of inclination of the heating conveyor from the horizontal plane is as a rule between 20xc2x0 and 45xc2x0.
Preferably, saturated steam is introduced in bursts into the treatment chamber and into the treatment screw conveyor. Injection in bursts achieves a pressure increase and a depth effect, since between the bursts of steam an expansion, especially of the material in the treatment chamber, is produced. An equal effect is achievable if microwave energy is introduced in bursts into moist material in the treatment chamber and/or the treatment conveyor.
It is provided within the scope of the invention that at the entrance into the heating screw conveyor a moisture sensor will measure the moisture content of the material, and that water will be added to the material in the necessary proportion, if required.
It is advantageous if, at the end of the heating screw conveyor the temperature of the material is measured and the driving means of the heating screw conveyor is controlled according to the temperature measured such that the holding time of the material in the screw conveyors and in the treatment chamber is assured.
Furthermore, provision is made so that a temperature sensor will track the temperatures occurring in the area at the entrance of the treatment conveyor and record and document them by means of a recording apparatus, so that the temperature program will be reproducible afterwards. It is thus possible to have proof even very much later that the material was treated as prescribed. If in the rear area of the treatment conveyor a temperature sensor is disposed by which the temperature of the material in this area is tracked and recorded by means of a recording apparatus it will be possible to evaluate the data in comparison with the recording made by the temperature sensor in the entry area of the treatment conveyor.
It may be advantageous if a conical ring is disposed in the end area of the heating screw conveyor and of the treatment conveyor to promote the compression of the material and the formation of the sealing plugs. An expansion of the material will then take place behind the ring.
In a preferred embodiment of the invention, the compression of the material is performed in the area of the screw conveyor and/or the treatment conveyor by means of a transport spiral. Here an especially good and safe formation of the sealing plug can be achieved, since on account of the lack of an internal worm shaft the material is driven with special intensity in the end area of the conveyors, where it is intensely compressed. This effect can be enhanced by performing the compression of the material in the screw conveyor and/or the treatment screw conveyor such that the pitch of the transport spiral decreases in the end area.
Within the scope of the invention it is also provided that, by means of a retention flap arranged at the end of the treatment conveyor an additional compression of the material occurs. Insofar as the additional compression is effected by means of a multi-part retaining flap, a continuously operating supplemental throttle gap is maintained.
Also it is advantageous if vapors emitted in the area of the discharge are sucked away by means of a suction duct.
A further optimization of the method of the invention is possible if a temperature sensor is disposed in the treatment chamber or in the inlet of the treatment conveyor by means of which the treatment temperature of the material is detected and the driving means of the treatment conveyor is regulated so as to maintain the optimum treatment temperature and treatment time.
The apparatus of the invention is furthermore characterized in that a first screw conveyor is provided which is configured as a heating screw conveyor surrounded by a heating element and in which a compression of the material takes place such that a sealing plug of material is produced in its end region, that at the end of the first screw conveyor a treatment chamber is disposed in which an expansion and loosening of the structure of the material takes place, that a second screw conveyor configured as a conveyor surrounded by a heating element for the material reaches into the treatment chamber, that energy bursts can be introduced into the treatment chamber and into the treatment conveyor, steam is delivered and/or produced, and an elevated pressure and the necessary temperature are built up and maintained, and that the treatment screw compresses the material in its end region to form a second sealing plug of material, such that the elevated pressure can be maintained for a defined period of time between the two material plugs of the screw conveyors which act as seals.
Within the scope of the invention provision is made for the heating screw conveyor and/or the treatment screw conveyor to be formed by a transport spiral which is mounted on slide rails extending lengthwise along the inner walls of the screw housing. In that case it can be advantageous if the pitch of the heating screw conveyor and/or of the treatment screw is reduced in the end regions thereof.
In accordance with one preferred embodiment of the invention, the heating screw conveyor is arranged in the apparatus extending at an upward angle in the direction of flow. This prevents unacceptably large amounts of liquid from being fed into the treatment chamber or into the treatment screw. Preferably the heating screw conveyor is oriented at an upwardly inclined angle of 20 to 45xc2x0.